Republican nominee Donald Trump rode a message of populist anger to a remarkable presidential victory made possible by insurgent successes in the US industrial heartland.
Trump vowed to serve as a leader for "all Americans" and called for the country to "bind the wounds of division" after a contentious presidential campaign.
"I say it is time for us to come together as one united people," Trump said flanked by his family as he addressed supporters in New York.
He said Democrat Hillary Clinton, who would have become the first female president in the country's history, had called to concede the election after Trump's surprise upset.
"I pledge to every citizen of our land, that I will be president for all Americans," he said, vowing to reach out to former opponents for guidance and support.
Trump's unexpected sweep of states including of Florida, Pennsylvania, Ohio and Wisconsin scrambled the electoral college math and gave him the necessary majority in electoral votes over Clinton, major US media projected.
Clinton entered Tuesday's election with a narrow lead in most nationwide surveys of likely voters and had been the favourite to win the electoral vote, propelling
Trump scored crucial victories in other hard-fought states including North Carolina and Florida, the largest prize of the so-called swing states.
With more than 110 million votes cast, Trump led 48.1 per cent to 47.2 per cent in the popular vote, which does not decide the race.
Republicans, who entered the general elections with majorities in Congress, appeared to have retained control of both the lower House of Representatives and the Senate.
Trump's often inflammatory rhetoric and impulsive tweets dominated the campaign since he declared his candidacy in June 2015.
Trump, who for months was not taken seriously by the Republican establishment, eventually overcame 16 other candidates vying for the conservative party's presidential nod.
Even after officially accepting the Republican nomination in July, he struggled into the final weeks of the campaign to consolidate the conservative party's base.
Attracted by his hostility to immigrants and trade, many of Trump's core supporters are disaffected white independents, who compared to the entire US population are older, less educated and disproportionately male.
Democrats accused him of bigotry toward Latinos, Muslims and other minorities.
During the campaign Trump's mostly unscripted comments angered military veterans, handicapped people and women. The October revelation of a recording in which the real estate tycoon claimed to have made lewd advances on women unleashed a flurry of accusations of sexual harassment and assault against him.
Clinton was bidding to return to the White House, which she and her husband, former president Bill Clinton, occupied from 1993-2001.
A long-running FBI investigation of Clinton's handling of classified emails while serving as secretary of state from 2009-13 dogged her campaign.
The winner will be sworn into office as the 45th US president on January 20 to succeed Barack Obama, the first African-American president.
